Towers for treating stock, substantially for the continuous bleaching of cellulose pulp or for the storing of such pulp



R. H. FRYKHULT 3,053,067 THE Filed June 29. 1960 2 Sheets-Sheet 1 INVENTOR ept. 1 6 R. H. FRYKHULT 3,053,067

TOWERS F OR TREATING STOCK, SUBSTANTIALLY FOR THE CONTINUOUS BLEACHING 0F CELLULOSE PULP OR FOR THE STORING OF SUCH PULP 2 Sheets-Sheet 2 Filed June 29. 1960 I! 1 wall! I?! III I!!! United States Patent 3,053,067 TOWERS FOR TREATING STOCK, SUBSTANTIAL- LY FOR THE CONTINUOUS BLEACHING 0F CELLULOSE PULP OR FOR THE STORING OF SUCH PULP Rune Helmer Frylrhult, Sundsbruk, near Sundsvall, Sweden, assignor to Sunds Verkstader Aktiebolag, Sundsbruk, Sweden Filed June 29, 1960, Ser. No. 39,666 Claims priority, application Sweden June 30, 1959 3 Claims. (Cl. 68-481) In towers used for the treatment of stock in the cellulose industry the pulp usually is caused to flow through the towers, in the longitudinal direction thereof, either from below upwards or vice versa. Whichever may be the direction of flow of the pulp there exist, in cases when the height of a tower is small in relation to the diameter thereof, difiiculties in causing the pulp to flow at equal speedat each cross sectional area of the tower. Different speeds of flow of the pulp in the tower usually cause so-called channeling within the pulp. If the heights of the towers could be made smaller in relation to the diameters of the towers than what has hitherto been the case, i.e. if the towers could be made lower while maintaining the same cubic capacity, this would result in a reduced pump work and in many cases also in a saving due to a reduced volume of building.

According to the present invention which, in the first place, is intended for cases in which the flow of the pulp through the tower takes place from below upwards and which has for its object to prevent channeling within the pulp, the problem has been solved in that way that, inside, the tower is provided with at least two ducts for guiding the stock within the tower.

These and other characteristic features of the invention will appear from the following detailed description, reference being had therein to the figures of the accompanying drawings in which FIGURE 1 is a vertical sectional view of a tower in accordance with the invention with longitudinal passage ducts extending over the whole length of the tower,

FIGURE 2 is a section on the line II-II of FIGURE 1,

FIGURE 3 is a vertical sectional view of a second embodiment of the invention with the ducts extending only some distance upward within the tower,

FIGURE 4 is a section on the line IVIV of FIG- URE 3, and

FIGURE 5 is a vertical sectional view of an alternative embodiment of the upper portion of the tower.

In the embodiment shown in FIGURES 1 and 2, said embodiment being particularly suitable in connection with the treatm nt of pulp of a low degree of concentration, eg in chlorination towers in bleacheries, numeral 1 denotes the tower, numeral 2 denoting a stationary, curved supply pipe for pulp, which is introduced into the tower through a pulp distributing device 4, which is provided with a discharge duct 3. The distributing device 4 is embodied as a rotor, which through the duct 3 distributes the pulp uniformly in all radial directions at the bottom of the tower. By means of screens or partitions 5, extending along the whole length of the tower, the tower is divided into four ducts 6, the cross sectional area of each such duct having the contour of a sector of a circle, equal volumes of pulp being supplied to said ducts through the rotating distributing device (there may be any number of ducts and the cross sectional area of each duct may also have any geometrical contour). 7 indicates the driving device for the rotor 4 and 8 is the discharge pipe for the pulp at the top of the tower. The screens or partitions 5 may consist of thin sheet metal, because the filling of the ducts 6 with pulp, when starting the ice plant, on the whole takes place uniformly in all of the ducts. In order that the filling shall become equal in respect of all of the ducts the individual ducts may be caused to communicate with each other to some extent in the lower portion of the tower. Of course it is possible just as well to supply the pulp at the top of the tower and discharge it at the bottom. In that case the tower is to be turned so that the distributing device 4 will be located at the top and the discharge pipe 8' at the bottom.

FIGURE 3 shows an embodiment which is particularly suitable for use in connection with the treatment of pulp having a high degree of concentration. In this embodiment screens or partitions 11, dividing the tower 9 into ducts 10, are combined with a passage pipe 12, provided centrally within the tower, and a stationary guide body 13. 14 indicates a pump for pumping pulp, via a mixing device 15 (the latter being used only in case the pulp is to be mixed with chemicals or vapour) through an inlet pipe 16 to a rotatable, motor-driven pulp distributing device 17 for distributing the pulp on entering the tower. The motor for driving the pulp distributing device 17 is not shown but is only marked by a driving belt 19, indicated in dashed lines, said belt being connected to the rotary shaft 18 of the distributing device. Above the pulp distributing device 17 there is provided the above mentioned, stationary guide body 13, which in the embodiment shown has the shape of two abutting frusta of cones. The guide body 13 also serves as an encasing member for certain portions of the supply members and the discharge members for the pulp, inter alia for the portion 20 of the inlet pipe 16, said pipe extending through the wall of the guide body 13 and curving downwards towards the pulp distributing device 17, and also for the substantially horizontal discharge pipe 21 for the pulp, i.e. the pipe into which opens the central passage pipe 12. It is, of course, also possible to make the pipe 12 curving and to have the same, or an extension thereof, it any, extend out through the shell of the tower or through the bottom of the tower, the arcuate portion 20 then preferably being positioned within the guide body 13 and the discharge pipe 21 for the pulp being dispensed with. By providing the arcuate portion 20 of the inlet pipe 16 within the tower a gain, in respect of the height of the tower, is obtained in comparison with what has been the case in a hitherto used system, according to which said arcuate portion 20, which in case of high pulp concentrations must have a large radius of curvature in relation to the diameter of the pipe, has been positioned outside the tower and from below has extended to the pulp inlet in the central area of the tower or to the rotatable pulp distributing device or pulp supply device positioned in the central area of the tower. The guide body 13 is braced by means of a tube 22 secured to the interior wall of the tower, said tube also serving the purpose of providing for a complete symmetry outside the guide body in respect of that portion of the inlet pipe 16 which extends between the wall of the tower and the guide body. As will appear from FIGURE 3 the upward flow of the pulp within the tower is intended to take place in that space of the tower which surrounds the pipe 12, the downward flow of the pulp being meant to take place through the pipe itself. Various provisions may be made for feeding the pulparrived at the top of the towertowards the central portion of the tower and down into the passage pipe 1 2, the uppermost portion of which is widened conically. In the embodiment according to FIG- URE 3 there is a feed-screw 23 and above the latter there is provided a rotatbale scraping device 24, the main object of which being to move the pulp into the area of operation of the feed-screw 23. Both the feed-screw 23 and the scraping device 24 are arranged to be driven by motors (not shown) via driving belts 25 and 26, respectively, which are only indicated by dashed lines. In the embodiment illustrated in FIGURE there is a retatable scraping device 27, which also is driven by a motor (the motor is not shown, only the driving belt 28 is indicated by dashed lines), said device being adapted to feed the pulp towards the middle of the tower and down into the upper, conical portion of the pipe 12. The scraping device 27 may be provided with any number of arms 29., which preferably are hollow and which are provided with any number of holes or nozzles 30, so that they may serve as spraying members for diluting water. Such diluting water is supplied through a stationary pipe line 31 and through the hollow rotary shaft 32 of the scraping device, and is conveyed out into all of the arms 29 of the device or only into some of said arms, if so should prove desirable. Between the stationary pipe line 31 and rotary shaft 32 of the scraping device there is provided tightening means 33. It is possible also to provide a stationary annular spraying device for the purpose of facilitating the downward movement of the pulp within the passage pipe 12.

In case the concentration of the pulp is low or if the pulp has become considerably diluted at the top of the tower the pulp will flow downwards through the pipe 12 and out of the tower without any extra steps having to be taken, but in case of high pulp concentrations there must be provided in the discharge pipe 21 a disintegrator or some other similar dissolving means for the pulp or a feed screw or the like, which may be provided with disintegrating members, such screw being denoted by reference numeral 34. Also in the previously mentioned modification, according to which the passage pipe 12 is curved and extends out through the shell or the bottom of the tower 9, it is of course possible, in a corresponding manner, to provide in the last portion of the pipe a disintegrator or some kind of dissolving means and/or a feed-screw, which may be provided with disintegrating members. For the dilution, if any, of the pulp within the discharge pipe 21 at the bottom of the tower said discharge pipe is provided with a socket 35 (FIGURE 4) for the supply of diluting water. If not desired, dilution need not be done either atthe top of the tower or at the bottom of the tower. The pulp suspension is discharged through a second socket, denoted by 36.

, A bleaching tower, arranged in accordance with the foregoing description, is particularly suitable for use in, for instance, bleaching plants of the kind in which the filters are positioned at a low level, because the diluting of the pulp may then be done wholly or partly at the bottom portion of the tower, this involving a saving of pump work. In addition to an attractive appearance of the tower the further advantage is obtained that in plants of the kind in which the towers are situated in the open air there are no pipe lines, requiring insulation, extending from the tops of the towers and outside the towers for the rest. i

In order to eliminate the risk of channeling the diameter of the distributing device, i.e. the rotor 4, of course 4 must be in a certain relation to the diameter of the tower. Said flation preferably is of the or'dei 1:4. Thus, in case of a large diameter of the tower also the diameter of the rotor 4 will be comparatively large. The power consumption will increase considerably with increasing diameter of the rotor 4.

The arrangement in which the distributing device and the guide ducts are located at the top of the tower, may, fundamentally, be used also in towers which are meant to operate when not quite filled. Towers, in which the pulp is meant to flow from the top downwards need not be operated in a quite filled state (contrary to towers in which the pulp is meant to how from the bottom upwards), because it is possible hereby to reduce the time of reaction as one desires.

A number of modifications of the embodiments described may, of course, be devised within the scope of the invention, and also the arrangements, shown in the various figures, may be combined with each other. For instance, the invention includes the application thereof also to horizontal, i.e. lying, towers for the treatment of pulp.

Having now described my invention, what I claim as new and desire to secure by Letters Patent is:

1. A twer for the treatment of stock comprising a substantially closed cylindrical container, means for introducing stock into the containennieans for discharging stock from the container and means within the container defining at least two stationary ducts each of which is substantially closed along its whole length, the walls of the ducts extending axially of the container, the cross sectional area of each of said ducts being substantially the sector of a circle, the periphery of said circle being formed by the cross sectional periphery of said cylindrical container, said substantially closed ducts being located symmetrically around the axis of the container and one after the other when seen in the peripheral direction of the container, said ducts serving for guiding the stock during its passage through the container.

2. A tower as defined in claim 1 in which the ducts extend only a part of the length of the container. I 3. A tower as defined in claim 1 comprising a pipe located centrally in the container and eirtending longitudiiially thereof for conveying stock through the container in the direction opposite to its movement through said du'cts.

lief erences Cited in the file of this patent UNITED STATES PATENTS 1,433,865 Wolf 0a. 31, 1922 1,529,919 Richter Mar. 17, 1925 1,953,022 McComb's Mar. 27, 1934 1,960,513 Wolf er al. May 29 1934 2,078,810 Richter et al. Apr. 27, 1937 2,774,654 Reed l Dec. 18, 1956 FOREIGN PATENTS 81,817 Sweden Oct. 23, 1934 

1. A TOWER FOR THE TREATMENT OF STOCK COMPRISING A SUBSTANTIALLY CLOSED CYLINDRICAL CONTAINER, MEANS FOR INTRODUCING STOCK INTO THE CONTAINER, MEANS FOR DISCHARGING STOCK FROM THE CONTAINE AND MEANS WITHIN THE CONTAINER DEFINING AT LEAST TWO STATIONARY DUCTS EACH OF WHICH IS SUBSTANTIALLY CLOSED ALONG ITS WHOLE LENGTH, THE WALLS OF THE DUCTS EXTENDING AXIALLY OF THE CONTAINER, THE CROSS SECTIONAL AREA OF EACH OF SAID DUCTS BEING SUBSTANTIALLY THE SECTOR OF A CIRCLE, THE PERIPHERY OF SAID CIRCLE BEING FORMED BY THE CROSS SECTIONAL PERIPHERY OF SAID CYLINDRICAL CONTAINER, SAID SUBSTANTIALLY CLOSED DUCTS BEING LOCATED SYMMETRICALLY AROUND THE AXIS OF THE CONTAINER AND ONE AFTER THE OTHER WHEN SEEN IN THE PERIPHERAL DIRECTION OF THE 